Inkjet printing is a non-impact printing method that, in response to a digital signal, produces droplets of ink that are deposited on a recording element. Today, inkjet printing systems are used in a variety of capacities in industrial, home, and office environments. The quality of inkjet prints continues to improve, however, inkjet prints are disadvantaged because they lack durability, often being less stable relative to environmental factors (light, ozone, etc.) and more sensitive to water and abrasion.
One way of overcoming these disadvantages is to laminate or encapsulated inkjet prints. When an inkjet print is laminated, a transparent overlay is adhered to the inkjet print. Typically, this is accomplished using an adhesive activated by heat, pressure, or both. The transparent overlay physically protects the print and seals it from ingress of water. When an inkjet print is encapsulated, the print is positioned between two laminating sheets, at least one of which is transparent. Then some combination of the print and the laminating sheets are adhered usually using an adhesive activated by heat, pressure, or both. Typically, encapsulation is most effective when the laminating sheets extend beyond the print and are bonded to each other at the extremities, thus preventing ingress of water through exposed edges of the print.
Lamination and encapsulation both have disadvantages in that they are expensive processes requiring additional materials and handling by the user. Moreover, inkjet inks remained trapped within the recording element which can degrade image quality by causing stain or migration of the print on storage or exposure. Laminate materials and adhesives can often deteriorate over time causing surface defects including, for example, cracking. Laminates do not always adhere well to inkjet prints. The quality and uniformity of adhesion can depend on the material nature of the recording element, the type of ink, and the volume of ink printed per unit area of recording element (ink laydown). The latter is particularly significant when the inkjet print has photographic image quality because heavy laydowns of ink are necessary to achieve the necessary superb image quality.
As an alternative to lamination or encapsulation, inkjet recording elements having a nascent protective layer coated on a support are known. The nascent protective layer is really a special chemical layer designed such that during the inkjet printing process, the inks penetrate the layer, and after printing is complete, the layer is fused using heat and/or pressure so that it seals and protects the print. This process is often referred to as the incorporated approach because the nascent protective material is incorporated into the recording element during its production.
However, the incorporated approach is limited because it is difficult to obtain a final protected print that is uniform in gloss and clarity and free of surface defects such as blistering and cracking. Limitations are especially apparent when the final protected print must have superb image quality, e.g., when it is for photographic or medical diagnostic applications. A recording element for these applications may have one or more of these layers underlying the nascent protective layer to help manage a heavy laydown of ink. After printing, the bulk of the ink, commonly referred to as the carrier, is retained somewhere in the dual layer system. If too much carrier resides in the nascent protective layer during fusing, it will not fuse properly and any of the aforementioned undesirable effects may be observed.
This condition worsens when the carrier resides predominately in an ink-receiving layer during and/or after fusing of the nascent protective layer, and then migrates within the ink-receiving layer, or from the ink-receiving layer and into the fused protective layer. Migration of the carrier within the ink-receiving layer causes deterioration of image quality, e.g., loss of image sharpness and blotchiness, and migration into the fused protective layer causes any of the aforementioned undesirable effects.
Examples of inkjet printing methods that employ the incorporated approach are described in U.S. Pat. No. 6,114,020, issued to Misuda et al., on Sep. 5, 2000; U.S. Pat. No. 4,832,984, issued to Hasegawa et al., on May 23, 1989; and U.S. Pat. No. 4,785,313, issued to Higuma et al., on Nov. 15, 1988.
European Patent Application 1 284 186 A2 describes a fixing apparatus and an image fixing method for improving the gloss of an inkjet image recorded on an inkjet recording material. The inkjet recording material includes a porous top layer which can be thermally fixed. After the image has been printed, the recording material is held in “a suspended state” before it is passed between a pair of fixing belts or rollers that are held at some elevated temperature and pressure.
Japanese Unexamined Patent Publication 2002-283553 A describes an inkjet recording device for controlling the gloss and clarity of an image surface of a recording medium. The device includes inkjet printing means for generating a printed image on a recording medium and fixing means for heating and pressing the printed image. The recording medium has a thermoplastic resin layer that receives ink and is subsequently fixed.
U.S. Patent Application Publication 2002/0027587 A1 describes an apparatus and method for forming prints. A recording medium having thermoplastic resin particles on a surface layer is printed. Subsequently the resin particles are made transparent by a heating and pressing device. U.S. Patent Application Publication 2002/0008747 A1 describes a similar method.
U.S. Pat. No. 6,357,871 B1 describes an inkjet recording medium and apparatus for preparing an inkjet printed product. The inkjet recording medium has a layer of fine particles of a thermoplastic organic polymer that are dissolved or melted after inkjet recording to form a layer wherein the particles are fused to one another. Fusing the particles involves a step of heating the layer followed by an impressing step of passing the recording medium between a pair of press rolls while the layer is still in a plastic state after the heating step.
All of the aforementioned art are disadvantaged in that the bulk of the ink, or carrier, is trapped within the recording element after the protective layer is formed which leads to the problems described above. Therefore, there is a need for an apparatus and method that removes carrier from an imaged and/or printed recording element before the recording element is fused.
Japanese Patent Laid Open Application No. 57-120447, discloses a heating and drying device using far infrared rays having a spectrum of 4 um to 400 um in an inkjet recording apparatus. The radiant energy intensity has a peak at a wavelength around 3.5 um followed by a broad emission band having a wavelength range from 4 um to greater than 50 um. However, if such a far infrared dryer is used, both the ink and the recording medium are heated, resulting in a low efficiency for heating the ink image. Here, only 50% of ink carrier can be dried at a recording medium feeding speed of 0.5 cm per second, yielding a very slow drying speed. Also, as most of the radiant energy is used to heat the recording medium, image artifacts such as yellowing and cockle would occur.
European Patent Application 0284215 A1 discloses a method and apparatus for uniformly drying ink on a paper after it is printed by an inkjet print head. In this method, an elongated infrared lamp with tungsten filament is used as the heat source and is located at the symmetry axis of a semi-cylindrical reflector forming a paper transport path. As the printed paper is fed along the interior cylindrical surface of the heat reflector, the paper receives a uniform heat flux and is dried uniformly. However, the color temperature of the tungsten-filament lamp is in general between 2300° K. and 3400° K., producing an emission spectrum in the near infrared range (the corresponding wavelength for maximum emission is between 0.85 um and 1.26 um). As the emission spectrum of the lamp does not match the absorption spectrum of the aqueous ink (for water the wavelength for maximum absorption is about 3.0 um), low drying efficiency is resulted.
U.S. Pat. No. 5,428,384 discloses a heater blower system in a color inkjet printer. This system uses a combination of air blowing over the image side of the medium, together with a radiant heater to heat the underside of the medium during the printing of an image, resulting in the evaporation of the ink carrier from the medium. In addition, an exhaust fan and duct system is used to effectively remove the vapor thus generated from the printer. However, the ink droplets adsorbing to the medium are caused to spread by the draft from the blower. Thus, ink mist flies to spread in the blowing direction and adheres to the circumference of the printed images, leading to the degradation of image quality. Also, since the radiant heater is located in the printing zone, facing the print head, the ink accumulated on the nozzle plate and/or near the nozzle would be dried out causing erratic ejection of droplets and possibly failure of ejection.
U.S. Pat. No. 6,244,700 B1 discloses an inkjet recording apparatus with a fixing heater that radiates infrared radiation having a maximum value within a range of wavelength from 4 um to 10 um. This heater is formed by coating a complex film containing Si, Fe, Zr, Ti, and Mn on the surface of a ceramic heater. The heater is arranged in a position, facing the print head, to heat the recoding medium and ink carrier from the reverse side (not the image side) of the medium through a screen grid supporting the medium. This method provides a compact and efficient heating device for drying and fixing the image with a lesser dissipation of power. However, as the heater is located in the printing zone, facing the print head, the ink accumulated on the nozzle plate and/or near the nozzle would be dried out causing erratic ejection of droplets and possibly failure of ejection. Moreover, although the heater provides a broad band radiation in the range of 2 um-34 um, the peak of radiation at about 7 um does not match the infrared absorption of aqueous ink having its main absorption peaks at around 3.0 um and 6.1 um. As a result, the heating effect on the ink in not optimal.
WO 97/01449 discloses a method of treating a coated medium after it has been printed by an inkjet print head. It first uses a stream of steam at a temperature of 100° C. or over and for between 0.1 to 100 seconds, and then applies heat on the printed medium for between 0.1 and 100 seconds so that the surface temperature of the medium is between 60° C. and 150° C. However, the hot steam and the subsequent condensation of water would perturb the ink droplets adsorbing to the medium resulting in severe image degradation.
U.S. Pat. No. 6,120,199 describes an inkjet printing apparatus having a heating fixation unit and a fixing unit. The heating fixation unit includes a fan that blows heated air over the surface of an imaged recording medium in an attempt to dry the surface before it enters the fixing unit. While ink solvent is allowed to escape from the imaged recording medium, the amount of ink solvent removed cannot be adequately controlled. Therefore, the reliability of the apparatus is reduced.
U.S. Pat. No. 6,406,118 B1 discloses an inkjet recording apparatus having a post-printing heat fixing station that consists of both a conductive heating platen to heat the unrecorded face of the recording material and a fan blowing hot air generated by a halogen heater to heat the ink bearing face of the recording material. Consequently, both faces of the recording material are sufficiently dried to accelerate the ink penetration, and the fixing time is significantly reduced. However, the draft from the blower would perturb the ink droplets adsorbing to the recording material, resulting in the degradation of image quality.
There is a need for an apparatus and method that removes carrier from an imaged and/or printed recording element, and subsequently increases a durability characteristic of the imaged and/or printed recording element while optimizing and/or controlling the conditions for each depending on the requirements of the imaged and/or printed recording element being dried.